Muscle fibrillation 2009-09-29T08:23:48Z HP:0010546 SNOMEDCT_US:41405005 EMG: fibrillations on electromyogram Twitching Fine, rapid twitching of individual muscle fibers with little or no movement of the muscle as a whole as ascertained by electromyography (EMG). If a motor neuron or its axon is destroyed, the muscle fibers it innervates undergo denervation atrophy. This leads to hypersensitivity of individual muscle fibers to acetyl choline so that they may contract spontaneously. Isolated activity of individual muscle fibers is generally so fine it cannot be seen through the intact skin, although it can be recorded as a short-duration spike in the EMG. UMLS:C0231531 Abnormality of movement